Jeroen van Dongen

Coronary artery bypass grafting without cardiopulmonary bypass and without interruption of native coronary flow using a novel anastomosis site restraining device ("Octopus").

OBJECTIVEnThis study assessed the feasibility of coronary artery bypass grafting on the beating heart without interruption of native coronary blood flow using a novel anastomosis site restraining device.nnnBACKGROUNDnRecently, an end-to-side bypass technique was described that does not require interruption of flow in the recipient artery.nnnMETHODSnBy means of a suction device (Octopus), in 31 pigs the epicardium was grasped and immobilized through an arm contraption fixed to the operating table. In the first 15 consecutive pigs (study I), the two-dimensional motion of an epicardial beacon was monitored. In 16 subsequent pigs (study II), an internal mammary artery was grafted under the microscope in two steps to a proximal coronary artery segment, without cardiopulmonary bypass. First, the internal mammary artery was sutured end-to-side to the outside of the coronary artery. Secondly, an orifice was punched in the partitioning coronary wall by an excimer laser catheter introduced through a temporary side-branch of the internal mammary artery.nnnRESULTSnStudy II: During 43 suction periods in four anastomosis areas, immobilization was achieved for 15 to 169 min (>30 h in total) in 13 open- and 9 closed-chest procedures without hemodynamic deterioration. The area circumscribed by the edges of the beacon trajectory (area in which the anastomosis is to be tracked) was reduced from 73.0 +/- 43.0 mm(2) (mean +/- SD) to 1.3 +/- 0.5 mm(2) (p<0.001) in the open-chest and to 0.2 +/- 0.2 mm(2) in the closed-chest procedure. At 6 weeks, no myocardial or coronary suction lesions were found. Study II: Nonocclusive anastomosis surgery required 25 +/- 3 min. No leakage, serious arrhythmias, graft closure or hemodynamic deterioration occurred during the procedure or for 2 h after ligating the coronary artery proximally. At 6 weeks, all seven grafts were patent.nnnCONCLUSIONSnCoronary bypass on the beating heart without interruption of coronary flow is feasible. In both open- and in closed-chest procedures, the Octopus reduced anastomosis site motion to about 1 X 1 mm without adverse consequences.

Emergence in holographic scenarios for gravity

‘Holographic’ relations between theories have become an important theme in quantum gravity research. These relations entail that a theory without gravity is equivalent to a gravitational theory with an extra spatial dimension. The idea of holography was first proposed in 1993 by Gerard ׳t Hooft on the basis of his studies of evaporating black holes. Soon afterwards the holographic ‘AdS/CFT’ duality was introduced, which since has been intensively studied in the string theory community and beyond. Recently, Erik Verlinde has proposed that even Newton׳s law of gravitation can be related holographically to the ‘thermodynamics of information’ on screens. We discuss these scenarios, with special attention to the status of the holographic relation in them and to the question of whether they make gravity and spacetime emergent. We conclude that only Verlinde׳s scheme straightforwardly instantiates emergence. However, assuming a non-standard interpretation of AdS/CFT may create room for the emergence of spacetime and gravity there as well.

How dark matter came to matter

The history of the dark matter problem can be traced back to at least the 1930s, but it was not until the early 1970s that the issue of ‘missing matter’ was widely recognized as problematic. In the latter period, previously separate issues involving missing mass were brought together in a single anomaly. We argue that reference to a straightforward accumulation of evidence alone is inadequate to comprehend this episode. Rather, the rise of cosmological research, the accompanying renewed interest in the theory of relativity and changes in the manpower division of astronomy in the 1960s are key to understanding how dark matter came to matter. At the same time, this story may also enlighten us on the methodological dimensions of past practices of physics and cosmology.

The Epistemic Virtues of the Virtuous Theorist: On Albert Einstein and His Autobiography

Albert Einstein’s practice in physics and his philosophical positions gradually reoriented themselves from more empiricist towards rationalist viewpoints. This change accompanied his turn towards unified field theory and different presentations of himself, eventually leading to his highly programmatic Autobiographical Notes in 1949. Einstein enlisted his own history and professional stature to mold an ideal of a theoretical physicist who represented particular epistemic virtues and moral qualities. These in turn reflected the theoretical ideas of his strongly mathematical unification program and professed Spinozist beliefs.

Introduction: Epistemic Virtues in the Sciences and the Humanities

Epistemic virtues offer a promising angle for studying interaction between fields of research conventionally classified under the “sciences” and the “humanities.” Given that virtues like objectivity, honesty, and accuracy are not confined to specific disciplines, they allow for comparative historical research between scientific fields as well as for histories of transfer, borrowing, and adaptation between disciplines. Such research, however, requires ample attention to what scientists in specific settings understood epistemic virtues to mean. Although the adjective refers to their role in facilitating the pursuit of epistemic aims (knowledge and understanding of reality), epistemic virtues are often imbued with moral, social, religious, and/or political meaning. If virtues specify the character traits marking a “scientific self,” then scientific selfhood is never exclusively defined in epistemic terms.

Albert Einstein and the History and Philosophy of Science

S cholarship that addresses the science and life of Albert Einstein is experiencing a remarkable year in 2015. As in 2005, Einstein is honored by centenary celebrations, this time recognizing the hundredth birthday of the general theory of relativity (1905, Einstein’s “miracle year,” had produced a less general version of the theory, along with other key ideas, such as the light quantum). Furthermore, Einstein scholarship may celebrate the highly anticipated appearance of The Cambridge Companion to Einstein. Here, then, we have good reason to pause and consider what the Companion may teach us about what the last ten years have brought and where Einstein scholarship stands today. The Companion proves to be a landmark publication. The editors, Michel Janssen and Christoph Lehner, rightly state in their preface that “physicist” might not be the right category for characterizing Einstein. Encompassing fourteen essays, this volume sets out to present Einstein as a scholar whose work and ideas crossed disciplinary boundaries, some of which were firmly established only during the second half of the twentieth century. Einstein’s interests were wide ranging, including the foundations, epistemology, and methodology of physics as well as technology, Zionism, and pacifism. The lion’s share of the Companion, however, is devoted to Einstein’s physics and its relation to his philosophy of science. Ten chapters analyze Einstein’s writings on the topics of general and special relativity, the quantum enigma, statistical mechanics, relativistic cosmology, and his attempts at unification theories. Three chapters focus on Einstein’s thought in philosophy of science in general. A final chapter discusses Einstein’s politics. The chapters on statistical mechanics and Brownian motion by A. J. Kox and on the light quantum by Olivier Darrigol and Roger Stuewer are fine examples of conceptual history, based on a solid grasp of the physics involved. Kox neatly and convincingly shows that Einstein’s work in statistical physics was guided “(1) by a strong belief and (2) by an important insight” (p. 103): his solid belief in atoms and his innovative uses of “fluctuation” methods to buttress his atomism. Indeed, whereas earlier scholars often shunned fluctuations—deviations from the mean in macroscopic quantities owing to the presumed microscopic nature of matter—Einstein explicitly used them to dramatic effect when he calculated the size of atoms,